PMS colors or the Pantone Matching System color guides are a mystery to most people and taking some time to understand the theory behind the system and how it relates to t-shirt printing will go a long way in satisfying the end user’s expectations.
Different Pantone Books
So let’s take a minute and look at two different color guides. If you were to compare the coated paper guide and the uncoated paper guide side by side you would see a distinct difference in colors of the same color number. Now I know many people think pms 129C is a different color than pms 129U when in fact they are the same ink color only printed on different types of paper. And the ink will look different again when printed on matt paper. And to make things more confusing often times colors are being selected using a computer monitor, which all display differently, and monitors display in RGB color which is totally different than CMYK color which is how digital paper printing is produced.
The Color of the Substrate
So what does all this have to do with t-shirt printing you’re probably asking? We’ll first off you have to realize that pms books are a guide to match colors to a desired consistency. The biggest challenge on t-shirts is the ever changing substrate color. So for best results, use the coated color guide for t-shirt printing on all shirts that will have an under base which will more closely match coated paper. And use the uncoated guide for shirts printed without an under base (usually only white shirts) which will match the uncoated colors better. But even with this in mind, note how differently pantone inks look when printed on two pieces of white paper and imagine trying to match a color printed on a dark shirt with a layer of white ink for a base then a bright color on top. Close matches are achievable but exact matches are often not.
Why Colors Look Different on an Underbase
So by now you are probably asking why wouldn’t a color printed on a white shirt look the same as when printed on a dark shirt with a white base? Well, the white shirt is porous and absorbs the ink and also gives the ink a matt type of look which usually darkens the color somewhat. The dark shirts with a white base are no longer porous and do not absorb the ink. Additionally all inks are somewhat translucent and allow some of the under color to illuminate through the top color which alter the appearance of the ink, especially darker colors on the lower half of the pantone guide which have little white in the mix.
When printing mid to dark colors on an underbase make sure to consult with an experienced printer for help in choosing the best colors for your project.